What do you mean by 16"? Frame size or wheel size? (sorry I'm not a bike person)
I have 3 little boys bikes in my garage which my boys had when they were 6 & 8 ish. They are a bit tatty & would need tyres pumping up etc but you are welcome to any/all of them if you like. The smallest one has a wheel of 12" & I think the largest one is 13" but the seat/pedal distance is 16". (Middle one is green/yellow and the other 2 are shocking pink).